As a (SNR scalable) method for coding an image according to conventional technique, transformation coefficients (acquired by executing frequency transformation to the image) are divided into each bit plane of one bit, and each bit plane is subjected to arithmetic coding. However, in this method, processing load thereof becomes high because the arithmetic coding is executed to each bit plane.
Furthermore, as another method for coding an image according to conventional technique, transformation coefficients (acquired by executing frequency transformation to the image) are divided into a high-order bit and a low-order bit. The high-order bit is coded without coding the low-order bit. However, in this method, coding efficiency is low because the high-order bit of the transformation coefficients is only coded.